Lifting-jack.



W. McH. ALSTON & LE. HINDMAN.

LIFTING JACK.

APljLlCATlON FILED MAR. 3. 1915.

Patented Dec. 28, 1915.

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W McH. ALSTON & I. E. HINDMAN.

LIFTLNG JACK.

APPLICATION EILED MAR. 3, 1915.

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25 All a 'h r s a--- WITNESSES v v ll;VE l;|TOR$ 2 mmmmm f d a v (a wfi g l WALTER McI-I. ALSTON, OF BEN AVON, A ND ISAIAH E. HINDMAN, OF OAKMONT, PENN- SYLVANIA, ASSIGNORS TO THE DUFF MANUFACTURING COMPANY, OF PITTSBURGH, PENNSYLVANIA, A CORPORATION OF PENNSYLVANIA.

LIFTINGr-J'ACK.

Specification of Letters Patent. Patented Dec. 28, 1915.

Application filed March 3,1915. Serial No. 11,718.

To all whom it may concern:

Be it known that we, WALTER MCH. ALs- TON and ISAIAH E. HINDMAN, both citizens of the United States, residing, respectively, at Ben Avon and at 'Oakmont, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvei nent in Lifting-Jacks, of which the followmg is afull, clear, and exact description, reference being had to the accompanying drawings, forming part of this specification,

Figures. 1 and 2 are side views, with the cap plates removed, of portions of a lifting jack embodying our invention, the two views showing the parts in different positions, and Fig. 3'is a section on the line IIIIII of Fig. 1.

Our'invention has .relation to lever-actu- 'ated lifting jacks; and is designed to provide a simple, novel and efficient arrangement of the actuating lever and pawl mechanism, and of the means for reversing the action of the pawls.

,A ,further object of the invention is to so mount andarrange the pawl and reversing mechanisms that they will be entirely independent of the removable cap plate or shield so as to be capable of complete operation, should the shield be removed or lost. Referring to the accompanying drawings, in which we have illustrated a preferred embodiment of our invention, and whichwill now be described, the numeral 2 designates .the usual lifting bar mounted for vertical movement in the frame 3, and having the ratchet bar 4 at one edge.

5 designates the actuating lever pivoted on the trunnions 6.

7 is the upper pawl mounted on a pivot 8 carried bythe heel of the lifting lever, and 9 is the lower pawl pivoted. at 10 to the frame. To receive the .inner portion of the lever, together with the pawl mechanism, the-jack frame is formed with the housing or pocket portion 11 having the two vertical substantially parallel plates or webs 11 and 11*, which carry the bearings .7 and 9 is a rod or stem 15, these rods or stems being connected to opposite arms of an equalizing lever 16 which is pivoted at 17, intermediate its ends, to the upwardly extending arm of an angle lever 18. The rods 15 are connected to the equalizing lever by means of swivel pins or studs 19;

and between each of these studs and the point of connection of the rod or stem with the pawl is seated a coiled spring 20. Each of these springs is fixed at each end. The angular lever 18 is pivoted at 21 and has therein a cam-shaped slot 22 which is engaged by a pin or stud 23 of a reversing lever 24 which depends and works through a slot 25 in the lower portion of the pocket or housing. The stems 15, equalizing lever 16, angle lever 18, and reversing lever 24 are all mounted in the space or pocket 13 before referred to, and are all entirely independent of the cap plate or shield 14. That is to say, none of the bearings or supports for any of the parts are in any way dependent upon this' cap plate, nor is the cap plate necessary in order to .hold any of the parts in' their proper working positions. In fact, the sole function of this cap plate is to prevent the entrance of dirt into the working parts; and the jack can be operated indefinitely with this plate removed.

* Fig. 1 shows the pawl mechanism with the parts in position for raising the lifting bar; while in Fig. 2 the pawls have been reversed to the positions they occupy when lowering the lifting bar and its load.

With the-partsin the positions shown in Fig. 1, the springs 20 are both in compression and are tending to hold the pawls 7 and 9 in engagement with the ratchet teeth 4. When the lever is moving downwardly the upper pawl 7 is in lifting engagement .With the teeth of the ,rack bar, the lower pawl 9 being in position to be forced in by it's spring to hold the load as soon as it is released by the pawl 7. On the reverse movement of the lever 5 the pawl 7 will swing away from the teeth 4 in position to get a new gripthereon, while the pawl 9 is holding the load. TlllS general operation is well known in jacks of this character.

When the lever 24 is moved from the position shown in Fig. l to the position shown in Fig. 2, the lever 18 is also shifted to the position shown in Fig. 2, which places both springs 26intension. -When the lever 5 moves downwardly, the pawl 7 is drawn away from the ratchet teeth 4 by the action of its spring 20, while the pawl 9 is held in by contact with the heel end of the lever 5. On the reverse stroke of the lever 5, pawl 7 is positively forced into en-' gagement with the teeth 4 by a projection 26 on the frame, and thereafter pawl 9 is relieved so that it can be retracted by its spring 20.

The cam slot 22in the' angle'lever 18 is preferably formed at each end with an offset depression 22*, which act to hold the pin or stud 23 in its respective positions, and there- 'nism,orto act as a guard to hold said parts against undue movement. In such cases the jack cannot be operated with the cap-plate removed; and if it is removed and lost, the entire jack is useless. until it is replaced. Furthermore, it is often desirable .to watch the operation of the parts. This cannot be done with the cap plate or shield in place and if the cap plate is removed it'cannot, of course, be done; Our invention overcomes these difiiculties by making the mechanism entirely independent of such plate. The pawl reversin mechanism is also extremely simple and e cient in its character and arrangement.

We claim:

1. In a lifting jack, the combination of a lifting 'bar, an actuating lever, upp'er' and lower pawls, an equalizing lever connecting the pawls, a spring interposed between each pawl and the equalizing lever, a pivoted lever member connected to the equalizing member, and a reversing lever operatively engaging said lever, substantially as described.

2. Ina lifting jack, the combination of a lifting bar, an actuating lever, upper and lower pawls, an equalizing lever connecting the pawls,' a pivoted lever member connected to the equalizing member, and I a reversing lever operatively engaging said lever, together with springs for the pawls adapted to be placed in compression in one position of the reversing lever, and in tension in the other position of the reversing lever, substantially as described.

3. In a lifting jack, the-combination of a lifting bar, an operating lever, upper and lower pawls, springs therefor, an equalizing connection between the pawls and a pivoted angle lever connected to the equalizing connection intermediate the two pawls and having a cam slot therein, and a reversing lever having .a portion which engages said slot to thereby actuate the angle lever and reverse 1 the pawls, substantially as described.

4. In a lifting jack, the combination of a lifting bar, an operating lever, upper and lower pawls, springs therefor, an equalizing connection between the pawls and ,a pivoted angle lever connected to the equalizing connection intermediate the two pawls and havinga cam slot therein, and a reversing lever having a portion which engages said slot to thereby actuate the angle lever and reverse the pawls, said parts being allmounted on a permanent portion of the jack frame, substantially as described.

5. A lifting-jack having a pocket or'h'oii'sing. therein to form substantially parallel web portions, a removable cap plate for one side of the housing or pocket, an operating lever pivoted between said web portions, upper andlower'pawls,.and an equalizing connection between the pawls, a lever member pivoted to one of the web portions of the casing and connected to said equalizing connection, and a reversing lever also pivoted to said web portion to operatively engage said lever' member, said parts being independent of the removable cap plate, substantially as described.

6. In a lifting jack, the combination of a lifting bar, an actuating lever, 'an upper pawl pivoted to the heel portion of the actuating lever, a lower pawl pivoted to the jack frame, a rod pivotally connected to each pawl, an equalizing lever having a swivel connection with each of said rods, a spring interposed between each end portion of the equalizer and the adjacent pawl, and reversing means engaging the equalizing lever; substantially as described.

mom I 7 A lifting iack having upper and lower In'testimony whereof, We have hereunto pawls, an equalizing connection between the setour hands.

two pawls said connection including spring means thei'ein, a lever member having one WALTER ALSTON' arm pivoted to the frame and another arm I I ISAIAH HINDMAN' pivotally connected to the equalizing lever, Witnesses: and a reversing device engaging said lever GEO. A. YOUNG,

member; substantially as described. Jos. A. LANE. 

